Tetrastigma　hemsleyanum　Diels　&　Gilg,　a　well-known　traditional　Chinese　medicine,　possesses　antitumor　and　anti-inflammatory　activity,　etc.　However,　the　anti-diabetic　effect　has　not　been　determined.　In　our　present　study,　a　water-soluble　polysaccharide,　named　THP　with　molecular　weight　of　93307Da,　was　isolated　from　T.　hemsleyanum　by　DEAE-52　ion-exchange　and　Sephadex　G-100　chromatography.　It　contains　rhamnose,　arabinose,　mannose,　glucose,　and　galactose　in　the　molar　ratio　of　0.07:0.14:0.38:0.21:0.31.　Then　anti-diabetic　effects　of　THP　were　examined　by　treating　alloxan-induced　diabetic　mice　with　different　doses　(100,　200,　and　300mg/kg)　of　THP　orally.　The　results　showed　that　THP　could　decrease　the　blood　glucose,　TC,　TG,　LDL-C　levels,　increase　the　body　weight,　HDL-C,　insulin　levels,　and　enhance　the　activities　of　antioxidant　enzyme　system　in　alloxan-induced　diabetic　mice.　Furthermore,　the　histopathological　examination　of　pancreas,　liver,　and　kidney　indicated　that　THP　could　protect　and　reverse　-cells　in　diabetic　mice　with　low　damage　to　liver　and　kidney,　which　suggests　that　THP　may　stimulate　pancreatic　release　of　insulin　and　can　be　an　effectively　potential　candidate　for　diabetes　mellitus.